Air jack with lubricating means



Aug. 23, 1966 H. o. FEILBACH ETAL 3,268,298

AIR JACK WITH LUBRICATING MEANS Filed Nov. 14, 1963 22. 42 'zz v 42 INVENTORS Ham/ex o. Femeaca DOUGLAS E. STUART BY F\ a. l o z w. m a

ATTORNY United States Patent 3,268,288 AIR JACK WITH LUBRICATING MEANS Harvey O. Feilbach, Milwaukee, and Douglas E. Stuart, Okauchee, Wis., assignors to Heirs-Werner Corporation, Waukesha, Wis., a corporation of Wisconsin Filed Nov. 14, 1963, Ser. No. 323,626

3 Claims. (Cl. 2542) This invention relates generally to improvements in air jacks and particularly to an improved air jack design wherein a new and improved arrangement for lubricating the piston in the cylinder is provided.

Proper lubrication of the pneumatically operated piston in an air jack has been a problem for many years. In prior designs the standard approach was to provide a felt washer mounted on the upper side of the piston and to supply such felt washer with lubricating oil from above the piston. In some constructions the piston was formed to provide an oil reservoir on the top portion thereof to thus supply the felt Washer. In all such arrangements, however, the oil applied would 'be quickly carried down past the edges of the piston and would thus be depleted in a rather short time.

The primary object of this invention is to provide an improved air jack construction wherein the piston will be effectively lubricated over a long period of time to thus insure proper operation without constant additions of oil.

Other objects and advantages will be pointed out in, or be apparent from, the specification and claims, as will obvious modifications of the single embodiment shown in the drawings, in which:

FIG. 1 is a fragmentary side elevation view of an air jack embodying the invention of this application;

FIG. 2 is a fragmentary elevation view taken from the rear of the jack shown in FIG. 1;

FIG. 3 is a fragmentary sectional view taken through the top portion of the jack; and

FIG. 4 is a sectional view taken through the lower portion of the jack.

As shown in FIG. 1, the air jack of this invention is comprised of a frame member on which an air cylinder 12 is fixedly mounted. An operating lift piston assembly 14 is slidably mounted in cylinder 12 and includes a piston rod 16 which extends upwardly and out the top of the cylinder for connection to a carriage assembly 18 by means of a pair of link members 20 and a cross tie member 22 secured to the top of the rod as clearly shown in FIG. 3. Saddle assemblies 24 equipped with saddle pads 26 are mounted on a carriage 18 for lifting a load when the piston is actuated. The frame is provided with a pair of rear support wheels 28 and front casters 30 to facilitate movement of the jack with respect to the load to be lifted. Handles 32 mounted at the top of the cylinder are provided to facilitate movement of the jack.

Air for energizing the piston to lift a load is supplied through a conduit 34 which connects to the lower portion of cylinder 12 through a fitting 36- as shown in FIG. 4. A pair of air control valves 38 and 40 mounted at the top of the cylinder (FIG. 2) and serve to control the flow of air to and from the cylinder to thus control the movement of the piston. The operation of valves 38 and 40 is controlled by a valve actuator 42 pivotally mounted adjacent the valves as shown in FIG. 2.

Reference is now made to FIG. 4 which shows the detailed construction of the novel piston assembly of this invention. Such assembly is shown in its down or unenergized position and includes a piston head plate 44, a sealing cup member 46, and felt lubricating washer 48, all mounted on the threaded end portion 50 of rod 16 and held securely in place by a nut 52. Head 44 may be of any suitable design and in the preferred embodiment shown in FIG. 4 is made from a circular steel plate 3,263,208 Patented August 23, 1966 having an outside diameter slightly less than the inside diameter of the cylinder to permit free sliding movement of the piston in the cylinder.

Cup member 46 is also of circular shape and in the preferred embodiment is made of rubber. Member 46 is provided with an annular flange portion 54 which is dimensioned to fit in snug contact with the inside wall of the cylinder 12 to thus prevent leakage of air past the piston when the jack is being operated. Felt washer 48, it should be noted, is mounted on the underside of the piston and is dimensioned so that its peripheral edge is in continuous contact with the cylinder wall. While it is not essential to the proper operation of the jack, washer 48 is mounted against the bottom of cup member 46 with its outer edge in contact with the edge of flange 54 on cup member 46 so that: the washer will be deformed to provide a dished shape as shown. When so deformed, the washer will make a substantially line contact with the cylinder wall as at 56 to thus minimize wear. The inverted dished shape of washer 48 will also facilitate the flow of oil from the center portion of the washer to the outer edge thereof. A pair of dish-shaped metal washers 60, 60 are mounted on opposite sides of washer 48 to hold it securely in place.

Lubricating oil is supplied to washer 48 from below the piston by maintaining an oil reservoir 58 at the bottom of the cylinder. Oil from the reservoir is carried to washer 48 by the action of the air flowing into the cylinder 12 through conduit 34 and fitting 36- when the proper air valve is actuated to energize the piston. It has been found that by maintaining an oil level slightly below the air inlet as shown in FIG. 4, the rush of air into the cylinder will sufliciently agitate the oil 58 and cause some of it to be carried upwardly for deposit on washer 48 each time the jack is operated to raise the piston assembly from the position shown in the drawings. Thus, as long as an oil reservoir 58 is maintained in the bottom of the cylinder the piston will be very effectively lubricated. It will be appreciated that the oil in the reservoir will be depleted very slowly since any excess oil flow upwardly to washer 58 will drain back to the reservoir by gravity. It has been found that in normal operation the air jack of this invention can be operated indefinitely before replenishment of oil is required as opposed to approxmately 30-day mantenance required in prior designs. Since equipment of this type is often subject to poor maintenance practices, the present invention not only simplifies maintenance but more importantly insures good performance over long periods of time and greatly reduces the chances of excessive wear due to insufficient lubrication.

Although but one embodiment of the present invention has been illustrated and described, it will be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit of the invention or from the scope of the appended claims.

We claim:

1. An air jack comprising:

an air cylinder;

a lift piston assembly slidably mounted in said cylinder, said piston assembly including a piston head member and a piston rod fastened thereto and extending upwardly from the head member and out through the top of the cylinder, said assembly further including an inverted sealing cup member having a downwardly extending annular flange portion, said cup member mounted on the underside of said head member and a lubricating washer mounted on the underside of said sealing cup member with its peripheral edge overlying said annular flange portion on said cup member, said lubricating washer being concave with respect to the bottom of said air cylinder;

a load engaging assembly mounted exteriorly of said cylinder and operatively connected to said piston rod;

a supply of lubricating oil in the bottom of said cylinder; and

air supply means for supplying air under pressure into said cylinder at a point below said lubricating washer when said piston assembly is in its deenergized position, said air supply means adapted to direct air into said cylinder so that the rush of air into the cylinder will agitate the oil and cause some of it to be carried upwardly for deposit on said lubricating washer.

2. An air jack comprising:

an air cylinder;

a lift piston assembly slidably mounted in said cylinder, said piston assembly including a piston rod, a piston, and a lubricating washer mounted on the underside thereof with its exposed surface facing the bottom of said cylinder, said lift piston assembly further including an inverted sealing cup member having a downwardly extending annular flanged portion, said lubricating Washer mounted on the lower face of said cup member with its peripheral edge overlying said annular flanged portion to thereby cause said lubricating washer to be deformed slightly;

a load engaging assembly mounted exteriorly of said cylinder and operatively connected to said piston rod;

a supply of lubricating oil in the bottom of said cylinder with the level thereof maintained at a point beneath the lowermost level to which said lubricating washer moves when said lift piston is in its fully retracted position to thereby prevent direct contact between said washer and said oil supply; and

air supply means for supplying air under pressure into said cylinder at a point below said lubricating washer when said piston assembly is in its fully retracted position, said air supply means adapted to direct air into said cylinder so that the rush of air into the cylinder will agitate the oil and cause some of it to be carried upwardly for deposit on said Washer.

3. An air jack comprising:

an air cylinder; 5

a lift piston assembly slidably mounted in said cylinder, said piston assembly including a piston rod, a piston, and a lubricating washer mounted on the underside thereof with its exposed surface facing the bottom of said cylinder;

a load engaging assembly mounted exteriorly of said cylinder and operatively connected to said piston rod;

a supply of lubricating oil in the bottom of said cylinder with the level thereof maintained at a point beneath the lowermost level to which said lubricating washer moves when said lift piston is in its fully retracted position to thereby prevent direct contact between said washer and said oil supply; and

air supply means for supplying air under pressure into said cylinder at a point below said lubricating washer when said piston assembly is in its fully retracted position, said air supply means including an air inlet conduit mounted on the side of said cylinder and positioned to direct the flow of air under pressure across the top surface of the supply of lubricating oil in the bottom of the cylinder so that the rush of air into the cylinder will agitate the oil and cause some of it to be carried upwardly for deposit on said lubricating washer.

References Cited by the Examiner UNITED STATES PATENTS 1,455,841 5/ 1923 Kelly. 1,590,830 6/ 1926 Jewkes. 1,868,935 7/1932 Breneman. 1,955,635 4/1934 Kelly. 3,091,431 5/1963 Arnes et a1.

WILLIAM FELDMAN, Primary Examiner.

MILTON S. MEHR, Examiner.

O. M. SIMPSON, Assistant Examiner. 

1. AN AIR JACK COMPRISING: AN AIR CYLINDER; A LIFT PISTON ASSEMBLY SLIDABLY MOUNTED IN SAID CYLINDER, SAID PISTON ASSEMBLY INCLUDING A PISTON HEAD MEMBER AND A PISTON ROD FASTENED THERETO AND EXTENDING UPWARDLY FROM THE HEAD MEMBER AND OUT THROUGH THE TOP OF THE CYLINDER, SAID ASSEMBLY FURTHER INCLUDING AN INVERTED SEALING CUP MEMBER HAVING A DOWNWARDLY EXTENDING ANNULAR FLANGE PORTION, SAID CUP MEMBER MOUNTED ON THE UNDERSIDE OF SAID HEAD MEMBER AND A LUBRICATING WASHER MOUNTED ON THE UNDERSIDE OF SAID SEALING CUP MEMBER WITH ITS PERIPHERAL EDGE OVERLYING SAID ANNULAR FLANGE PORTION OF SAID CUP MEMBER, SAID LUBRICATING WASHER BEING CONCAVE WITH RESPECT TO THE BOTTOM OF SAID AIR CYLINDER; 